Recommended Imaging Modality for Temporomandibular Joint (TMJ) Evaluation
For TMJ evaluation, MRI is the gold standard for soft tissue disorders (disc displacement, ligament-capsule issues), while CBCT or CT is recommended for bone-related pathology.
Imaging Selection Based on Suspected Pathology
Soft Tissue Disorders
- Contrast-enhanced MRI is currently the best method to detect active TMJ inflammation and is considered the gold standard for evaluating ligament and articular capsule structures 1
- MRI provides superior visualization of the articular disc position, morphology, and congruity in both closed and open-mouth positions 2
- MRI can uniquely demonstrate joint effusion, bone edema, sclerosis, rupture of retrodiscal layers, and impairment of lateral pterygoid muscle 2
- For internal derangement of the TMJ disc (displacement with or without reduction), MRI is the imaging modality of choice 3, 4
Bone-Related Pathology
- CT or CBCT is the gold standard for bone lesion assessment and should be used when condyle and glenoid cavity involvement is suspected 1
- CBCT provides high-resolution multiplanar reconstruction of the TMJ with lower radiation dose compared to conventional CT, without superimposition of bony structures 3
- For TMJ bone disease, CBCT or CT scan is indicated in clinical cases with suspected condyle and glenoid cavity involvement based on medical history and clinical examination 1
Limitations of Conventional Radiography
- Panoramic radiography (OPT) and other conventional radiographic images are insufficient for assessment of TMJ structures 1
- Conventional radiography does not supply adequate information about joint components and ligament-capsule components (disc) 1
- Panoramic radiographs may reproduce the condyle-glenoid cavity relationships unreliably due to projection errors 1
Special Considerations
For Juvenile Idiopathic Arthritis (JIA)
- Contrast-enhanced MRI is specifically recommended for detecting active TMJ arthritis in JIA patients 1
- MRI should be considered for monitoring TMJ involvement in JIA patients 1
- Clinical examination alone may miss TMJ inflammation in up to 42% of cases, highlighting the importance of imaging 1
Advanced Imaging Techniques
- Dynamic (cine-mode) MRI allows for functional evaluation in addition to morphologic study of the joint 2, 5
- Fast low angle shot (FLASH) sequences can provide dynamic images of the TMJ in various phases of opening 5
- Registration of MRI and CBCT images can provide comprehensive evaluation of the relationship between articular disc and condyle 6
Common Pitfalls and Caveats
- The presence of a small amount of TMJ fluid and/or minor contrast enhancement may be considered normal variation rather than a sign of active TMJ arthritis 1
- Interpretation of MRI findings has an element of subjectivity and is influenced by technique, equipment, and reader expertise 1
- Using CBCT solely to obtain lateral and panoramic projections exposes patients to unnecessary radiation when the same information can be obtained with lower radiation dose techniques 1
- The diagnostic value of ultrasonography is strictly dependent on the examiner's skills and equipment used, making it less reliable than MRI or CT 3